Nonclassical interpolation in spaces of smooth functions
We prove that the fractional BMO space on a one-dimensional manifold is an interpolation space between C and . We also prove that is an interpolation space between C and . The proof is based on some nonclassical interpolation constructions. The results obtained cannot be transferred to spaces of functions defined on manifolds of higher dimension. The interpolation description of fractional BMO spaces is used at the end of the paper for the proof of the boundedness of commutators of the Hilbert...